package cn.shuibo.util;
import java.io.UnsupportedEncodingException;


public class Base64Utils {

    /**

     * Default values for encoder/decoder flags.

     */

    public static final int DEFAULT = 0;



    /**

     * Encoder flag bit to omit the padding '=' characters at the end

     * of the output (if any).

     */

    public static final int NO_PADDING = 1;



    /**

     * Encoder flag bit to omit all line terminators (i.e., the output

     * will be on one long line).

     */

    public static final int NO_WRAP = 2;



    /**

     * Encoder flag bit to indicate lines should be terminated with a

     * CRLF pair instead of just an LF. Has no effect if {@code

     * NO_WRAP} is specified as well.

     */

    public static final int CRLF = 4;



    /**

     * Encoder/decoder flag bit to indicate using the "URL and

     * filename safe" variant of Base64 (see RFC 3548 section 4) where

     * {@code -} and {@code _} are used in place of {@code +} and

     * {@code /}.

     */

    public static final int URL_SAFE = 8;



    /**

     * Flag to pass to {@link Base64OutputStream} to indicate that it

     * should not close the output stream it is wrapping when it

     * itself is closed.

     */

    public static final int NO_CLOSE = 16;



// --------------------------------------------------------

// shared code

// --------------------------------------------------------



    /* package */ static abstract class Coder {

        public byte[] output;

        public int op;



        /**

         * Encode/decode another block of input data. this.output is

         * provided by the caller, and must be big enough to hold all

         * the coded data. On exit, this.opwill be set to the length

         * of the coded data.

         *

         * @param finish true if this is the final call to process for

         * this object. Will finalize the coder state and

         * include any final bytes in the output.

         *

         * @return true if the input so far is good; false if some

         * error has been detected in the input stream..

         */

        public abstract boolean process(byte[] input, int offset, int len, boolean finish);



        /**

         * @return the maximum number of bytes a call to process()

         * could produce for the given number of input bytes. This may

         * be an overestimate.

         */

        public abstract int maxOutputSize(int len);

    }



// --------------------------------------------------------

// decoding

// --------------------------------------------------------



    /**

     * Decode the Base64-encoded data in input and return the data in

     * a new byte array.

     *

     * <p>The padding '=' characters at the end are considered optional, but

     * if any are present, there must be the correct number of them.

     *

     * @param str the input String to decode, which is converted to

     * bytes using the default charset

     * @param flags controls certain features of the decoded output.

     * Pass {@code DEFAULT} to decode standard Base64.

     *

     * @throws IllegalArgumentException if the input contains

     * incorrect padding

     */

    public static byte[] decode(String str, int flags) {

        return decode(str.getBytes(), flags);

    }



    /**

     * Decode the Base64-encoded data in input and return the data in

     * a new byte array.

     *

     * <p>The padding '=' characters at the end are considered optional, but

     * if any are present, there must be the correct number of them.

     *

     * @param input the input array to decode

     * @param flags controls certain features of the decoded output.

     * Pass {@code DEFAULT} to decode standard Base64.

     *

     * @throws IllegalArgumentException if the input contains

     * incorrect padding

     */

    public static byte[] decode(byte[] input, int flags) {

        return decode(input, 0, input.length, flags);

    }



    /**

     * Decode the Base64-encoded data in input and return the data in

     * a new byte array.

     *

     * <p>The padding '=' characters at the end are considered optional, but

     * if any are present, there must be the correct number of them.

     *

     * @param input the data to decode

     * @param offset the position within the input array at which to start

     * @param len the number of bytes of input to decode

     * @param flags controls certain features of the decoded output.

     * Pass {@code DEFAULT} to decode standard Base64.

     *

     * @throws IllegalArgumentException if the input contains

     * incorrect padding

     */

    public static byte[] decode(byte[] input, int offset, int len, int flags) {

// Allocate space for the most data the input could represent.

// (It could contain less if it contains whitespace, etc.)

        Decoder decoder = new Decoder(flags, new byte[len*3/4]);



        if (!decoder.process(input, offset, len, true)) {

            throw new IllegalArgumentException("bad base-64");

        }



// Maybe we got lucky and allocated exactly enough output space.

        if (decoder.op == decoder.output.length) {

            return decoder.output;

        }



// Need to shorten the array, so allocate a new one of the

// right size and copy.

        byte[] temp = new byte[decoder.op];

        System.arraycopy(decoder.output, 0, temp, 0, decoder.op);

        return temp;

    }



    /* package */ static class Decoder extends Coder {

        /**

         * Lookup table for turning bytes into their position in the

         * Base64 alphabet.

         */

        private static final int DECODE[] = {

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,

                52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,

                -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,

                15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,

                -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

                41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

        };



        /**

         * Decode lookup table for the "web safe" variant (RFC 3548

         * sec. 4) where - and _ replace + and /.

         */

        private static final int DECODE_WEBSAFE[] = {

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,

                52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,

                -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,

                15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63,

                -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

                41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

                -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

        };



        /** Non-data values in the DECODE arrays. */

        private static final int SKIP = -1;

        private static final int EQUALS = -2;



        /**

         * States 0-3 are reading through the next input tuple.

         * State 4 is having read one '=' and expecting exactly

         * one more.

         * State 5 is expecting no more data or padding characters

         * in the input.

         * State 6 is the error state; an error has been detected

         * in the input and no future input can "fix" it.

         */

        private int state; // state number (0 to 6)

        private int value;



        final private int[] alphabet;



        public Decoder(int flags, byte[] output) {

            this.output = output;



            alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE;

            state = 0;

            value = 0;

        }



        /**

         * @return an overestimate for the number of bytes {@code

         * len} bytes could decode to.

         */

        public int maxOutputSize(int len) {

            return len * 3/4 + 10;

        }



        /**

         * Decode another block of input data.

         *

         * @return true if the state machine is still healthy. false if

         * bad base-64 data has been detected in the input stream.

         */

        public boolean process(byte[] input, int offset, int len, boolean finish) {

            if (this.state == 6) return false;



            int p = offset;

            len += offset;



// Using local variables makes the decoder about 12%

// faster than if we manipulate the member variables in

// the loop. (Even alphabet makes a measurable

// difference, which is somewhat surprising to me since

// the member variable is final.)

            int state = this.state;

            int value = this.value;

            int op = 0;

            final byte[] output = this.output;

            final int[] alphabet = this.alphabet;



            while (p < len) {

// Try the fast path: we're starting a new tuple and the

// next four bytes of the input stream are all data

// bytes. This corresponds to going through states

// 0-1-2-3-0. We expect to use this method for most of

// the data.

//

// If any of the next four bytes of input are non-data

// (whitespace, etc.), value will end up negative. (All

// the non-data values in decode are small negative

// numbers, so shifting any of them up and or'ing them

// together will result in a value with its top bit set.)

//

// You can remove this whole block and the output should

// be the same, just slower.

                if (state == 0) {

                    while (p+4 <= len &&

                            (value = ((alphabet[input[p] & 0xff] << 18) |

                                    (alphabet[input[p+1] & 0xff] << 12) |

                                    (alphabet[input[p+2] & 0xff] << 6) |

                                    (alphabet[input[p+3] & 0xff]))) >= 0) {

                        output[op+2] = (byte) value;

                        output[op+1] = (byte) (value >> 8);

                        output[op] = (byte) (value >> 16);

                        op += 3;

                        p += 4;

                    }

                    if (p >= len) break;

                }



// The fast path isn't available -- either we've read a

// partial tuple, or the next four input bytes aren't all

// data, or whatever. Fall back to the slower state

// machine implementation.



                int d = alphabet[input[p++] & 0xff];



                switch (state) {

                    case 0:

                        if (d >= 0) {

                            value = d;

                            ++state;

                        } else if (d != SKIP) {

                            this.state = 6;

                            return false;

                        }

                        break;



                    case 1:

                        if (d >= 0) {

                            value = (value << 6) | d;

                            ++state;

                        } else if (d != SKIP) {

                            this.state = 6;

                            return false;

                        }

                        break;



                    case 2:

                        if (d >= 0) {

                            value = (value << 6) | d;

                            ++state;

                        } else if (d == EQUALS) {

// Emit the last (partial) output tuple;

// expect exactly one more padding character.

                            output[op++] = (byte) (value >> 4);

                            state = 4;

                        } else if (d != SKIP) {

                            this.state = 6;

                            return false;

                        }

                        break;



                    case 3:

                        if (d >= 0) {

// Emit the output triple and return to state 0.

                            value = (value << 6) | d;

                            output[op+2] = (byte) value;

                            output[op+1] = (byte) (value >> 8);

                            output[op] = (byte) (value >> 16);

                            op += 3;

                            state = 0;

                        } else if (d == EQUALS) {

// Emit the last (partial) output tuple;

// expect no further data or padding characters.

                            output[op+1] = (byte) (value >> 2);

                            output[op] = (byte) (value >> 10);

                            op += 2;

                            state = 5;

                        } else if (d != SKIP) {

                            this.state = 6;

                            return false;

                        }

                        break;



                    case 4:

                        if (d == EQUALS) {

                            ++state;

                        } else if (d != SKIP) {

                            this.state = 6;

                            return false;

                        }

                        break;



                    case 5:

                        if (d != SKIP) {

                            this.state = 6;

                            return false;

                        }

                        break;

                }

            }



            if (!finish) {

// We're out of input, but a future call could provide

// more.

                this.state = state;

                this.value = value;

                this.op = op;

                return true;

            }



// Done reading input. Now figure out where we are left in

// the state machine and finish up.



            switch (state) {

                case 0:

// Output length is a multiple of three. Fine.

                    break;

                case 1:

// Read one extra input byte, which isn't enough to

// make another output byte. Illegal.

                    this.state = 6;

                    return false;

                case 2:

// Read two extra input bytes, enough to emit 1 more

// output byte. Fine.

                    output[op++] = (byte) (value >> 4);

                    break;

                case 3:

// Read three extra input bytes, enough to emit 2 more

// output bytes. Fine.

                    output[op++] = (byte) (value >> 10);

                    output[op++] = (byte) (value >> 2);

                    break;

                case 4:

// Read one padding '=' when we expected 2. Illegal.

                    this.state = 6;

                    return false;

                case 5:

// Read all the padding '='s we expected and no more.

// Fine.

                    break;

            }



            this.state = state;

            this.op = op;

            return true;

        }

    }



// --------------------------------------------------------

// encoding

// --------------------------------------------------------



    /**

     * Base64-encode the given data and return a newly allocated

     * String with the result.

     *

     * @param input the data to encode

     * @param flags controls certain features of the encoded output.

     * Passing {@code DEFAULT} results in output that

     * adheres to RFC 2045.

     */

    public static String encodeToString(byte[] input, int flags) {

        try {

            return new String(encode(input, flags), "US-ASCII");

        } catch (UnsupportedEncodingException e) {

// US-ASCII is guaranteed to be available.

            throw new AssertionError(e);

        }

    }



    /**

     * Base64-encode the given data and return a newly allocated

     * String with the result.

     *

     * @param input the data to encode

     * @param offset the position within the input array at which to

     * start

     * @param len the number of bytes of input to encode

     * @param flags controls certain features of the encoded output.

     * Passing {@code DEFAULT} results in output that

     * adheres to RFC 2045.

     */

    public static String encodeToString(byte[] input, int offset, int len, int flags) {

        try {

            return new String(encode(input, offset, len, flags), "US-ASCII");

        } catch (UnsupportedEncodingException e) {

// US-ASCII is guaranteed to be available.

            throw new AssertionError(e);

        }

    }



    /**

     * Base64-encode the given data and return a newly allocated

     * byte[] with the result.

     *

     * @param input the data to encode

     * @param flags controls certain features of the encoded output.

     * Passing {@code DEFAULT} results in output that

     * adheres to RFC 2045.

     */

    public static byte[] encode(byte[] input, int flags) {

        return encode(input, 0, input.length, flags);

    }



    /**

     * Base64-encode the given data and return a newly allocated

     * byte[] with the result.

     *

     * @param input the data to encode

     * @param offset the position within the input array at which to

     * start

     * @param len the number of bytes of input to encode

     * @param flags controls certain features of the encoded output.

     * Passing {@code DEFAULT} results in output that

     * adheres to RFC 2045.

     */

    public static byte[] encode(byte[] input, int offset, int len, int flags) {

        Encoder encoder = new Encoder(flags, null);



// Compute the exact length of the array we will produce.

        int output_len = len / 3 * 4;



// Account for the tail of the data and the padding bytes, if any.

        if (encoder.do_padding) {

            if (len % 3 > 0) {

                output_len += 4;

            }

        } else {

            switch (len % 3) {

                case 0: break;

                case 1: output_len += 2; break;

                case 2: output_len += 3; break;

            }

        }



// Account for the newlines, if any.

        if (encoder.do_newline && len > 0) {

            output_len += (((len-1) / (3 * Encoder.LINE_GROUPS)) + 1) *

                    (encoder.do_cr ? 2 : 1);

        }



        encoder.output = new byte[output_len];

        encoder.process(input, offset, len, true);



        assert encoder.op == output_len;



        return encoder.output;

    }



    /* package */ static class Encoder extends Coder {

        /**

         * Emit a new line every this many output tuples. Corresponds to

         * a 76-character line length (the maximum allowable according to

         * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>).

         */

        public static final int LINE_GROUPS = 19;



        /**

         * Lookup table for turning Base64 alphabet positions (6 bits)

         * into output bytes.

         */

        private static final byte ENCODE[] = {

                'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',

                'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',

                'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',

                'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',

        };



        /**

         * Lookup table for turning Base64 alphabet positions (6 bits)

         * into output bytes.

         */

        private static final byte ENCODE_WEBSAFE[] = {

                'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',

                'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',

                'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',

                'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_',

        };



        final private byte[] tail;

        /* package */ int tailLen;

        private int count;



        final public boolean do_padding;

        final public boolean do_newline;

        final public boolean do_cr;

        final private byte[] alphabet;



        public Encoder(int flags, byte[] output) {

            this.output = output;



            do_padding = (flags & NO_PADDING) == 0;

            do_newline = (flags & NO_WRAP) == 0;

            do_cr = (flags & CRLF) != 0;

            alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;



            tail = new byte[2];

            tailLen = 0;



            count = do_newline ? LINE_GROUPS : -1;

        }



        /**

         * @return an overestimate for the number of bytes {@code

         * len} bytes could encode to.

         */

        public int maxOutputSize(int len) {

            return len * 8/5 + 10;

        }



        public boolean process(byte[] input, int offset, int len, boolean finish) {

// Using local variables makes the encoder about 9% faster.

            final byte[] alphabet = this.alphabet;

            final byte[] output = this.output;

            int op = 0;

            int count = this.count;



            int p = offset;

            len += offset;

            int v = -1;



// First we need to concatenate the tail of the previous call

// with any input bytes available now and see if we can empty

// the tail.



            switch (tailLen) {

                case 0:

// There was no tail.

                    break;



                case 1:

                    if (p+2 <= len) {

// A 1-byte tail with at least 2 bytes of

// input available now.

                        v = ((tail[0] & 0xff) << 16) |

                                ((input[p++] & 0xff) << 8) |

                                (input[p++] & 0xff);

                        tailLen = 0;

                    };

                    break;



                case 2:

                    if (p+1 <= len) {

// A 2-byte tail with at least 1 byte of input.

                        v = ((tail[0] & 0xff) << 16) |

                                ((tail[1] & 0xff) << 8) |

                                (input[p++] & 0xff);

                        tailLen = 0;

                    }

                    break;

            }



            if (v != -1) {

                output[op++] = alphabet[(v >> 18) & 0x3f];

                output[op++] = alphabet[(v >> 12) & 0x3f];

                output[op++] = alphabet[(v >> 6) & 0x3f];

                output[op++] = alphabet[v & 0x3f];

                if (--count == 0) {

                    if (do_cr) output[op++] = '\r';

                    output[op++] = '\n';

                    count = LINE_GROUPS;

                }

            }



// At this point either there is no tail, or there are fewer

// than 3 bytes of input available.



// The main loop, turning 3 input bytes into 4 output bytes on

// each iteration.

            while (p+3 <= len) {

                v = ((input[p] & 0xff) << 16) |

                        ((input[p+1] & 0xff) << 8) |

                        (input[p+2] & 0xff);

                output[op] = alphabet[(v >> 18) & 0x3f];

                output[op+1] = alphabet[(v >> 12) & 0x3f];

                output[op+2] = alphabet[(v >> 6) & 0x3f];

                output[op+3] = alphabet[v & 0x3f];

                p += 3;

                op += 4;

                if (--count == 0) {

                    if (do_cr) output[op++] = '\r';

                    output[op++] = '\n';

                    count = LINE_GROUPS;

                }

            }



            if (finish) {

// Finish up the tail of the input. Note that we need to

// consume any bytes in tail before any bytes

// remaining in input; there should be at most two bytes

// total.



                if (p-tailLen == len-1) {

                    int t = 0;

                    v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4;

                    tailLen -= t;

                    output[op++] = alphabet[(v >> 6) & 0x3f];

                    output[op++] = alphabet[v & 0x3f];

                    if (do_padding) {

                        output[op++] = '=';

                        output[op++] = '=';

                    }

                    if (do_newline) {

                        if (do_cr) output[op++] = '\r';

                        output[op++] = '\n';

                    }

                } else if (p-tailLen == len-2) {

                    int t = 0;

                    v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) |

                            (((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2);

                    tailLen -= t;

                    output[op++] = alphabet[(v >> 12) & 0x3f];

                    output[op++] = alphabet[(v >> 6) & 0x3f];

                    output[op++] = alphabet[v & 0x3f];

                    if (do_padding) {

                        output[op++] = '=';

                    }

                    if (do_newline) {

                        if (do_cr) output[op++] = '\r';

                        output[op++] = '\n';

                    }

                } else if (do_newline && op > 0 && count != LINE_GROUPS) {

                    if (do_cr) output[op++] = '\r';

                    output[op++] = '\n';

                }



                assert tailLen == 0;

                assert p == len;

            } else {

// Save the leftovers in tail to be consumed on the next

// call to encodeInternal.



                if (p == len-1) {

                    tail[tailLen++] = input[p];

                } else if (p == len-2) {

                    tail[tailLen++] = input[p];

                    tail[tailLen++] = input[p+1];

                }

            }



            this.op = op;

            this.count = count;



            return true;

        }

    }



    private Base64Utils() { } // don't instantiate

}